Aquifer systems are vital to the regions that overlie
them. The Edwards Aquifer (figure 1.2) underlies
the cities of San Antonio, San Marcos, and Austin
in south-central Texas. San Antonio is the largest
city in the United States whose water supply
comes principally from groundwater, distributed
throughout the city after being pumped from hundreds
of wells drilled into the Edwards Aquifer.
Water from these wells supports a population of
more than 2 million people.